Is there a way to use Zod to validate that a number has up to 2 decimal digits?

Question

I have an object with a numeric property. I'd like to make sure that the number has only up to 2 decimal digit.

e.g: 1 // good 1.1 // good 1.11 // good 1.111 //bad

Is there way to do that?

Looked at Zod's documentation and searched the web. Found that i could have done it easily if my property was a string. Not sure about number.

THen just convert your nubmer to string `${number}` or number.toString() — captain-yossarian from Ukraine, Jan 30 '23 at 13:53
Tnx for answering @captain-yossarianfromUkraine. At my case i cannot convert the value as the validating is done in a generic layer, i need to define my requirement as a part of the object's schema. WDYT? — Uri, Jan 30 '23 at 14:15
tnx @vera. do you think custom / refine are the right way to go here? was afraid that its a hack (?) — Uri, Jan 30 '23 at 15:03
tnx! if there's no other way / a "best practice" for that - this solution is fine by me. — Uri, Jan 30 '23 at 15:12

skyboyer · Accepted Answer · 2023-01-31T11:23:08.170

4

z.number().multipleOf(0.01)

will do the hack(yes, it can work with non-integer too!).

However, I worry about IEEE 754 representation issue(it even has its own name - but I forgot - and is not specific to JS), when

z.number().multipleOf(0.01).parse(0.1 + 0.1 + 0.1)

will throw, since 0.1 + 0.1 + 0.1 under the hood becomes 0.300000000004

Maybe refine() will be more reliable with checking against Number.EPSILON:

z.number()
  .refine(x => x * 100 - Math.trunc(x * 100)< Number.EPSILON)
  .parse(0.1 + 0.1  + 0.1) // ok

[upd] as @captain-yossarianfromUkraine noticed, Number.EPSILON should help with float-number thing

PS cannot evaluate this approach against z.custom() proposed by @vera

edited Jan 31 '23 at 11:23

answered Jan 31 '23 at 00:33

skyboyer

1

Try to use `Number.EPSILON` to handle `0.1+0.2` issue. See [example](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/EPSILON) which is taken from docs – captain-yossarian from Ukraine Jan 31 '23 at 07:24
1

@captain-yossarianfromUkraine you're right. I tried yesterday with EPSILON and comparison did return `false` to me. But today it's `true` ¯\\_(ツ)_/¯ – skyboyer Jan 31 '23 at 11:21
Tnx for this answer! Great! I'm actually fine with '0.1 + 0.1 + 0.1' to fail, i'm getting an object with a number property. This number has to be with only up to two decimal digits, I don't care how it was created, if my api's user got `0.300000000004` because he/she added '0.1 + 0.1 + 0.1' and did not validate at his side that there are more decimal digits its his own problem. tnx again! – Uri Feb 01 '23 at 05:04

1 Answers1